ue al 
Mise i On Plaister of Paris, 
subject, the current opinions of the day. These, like the 
doctrine of phlogiston, though once held to be so strictl es 
orthodox, may, ere long, become apocryphal ; and be placed, 
by future reformers in chemistry, among the lumber of the 
schools. Something useful, however, is always added to the 
common stock of knowledge and improvement, by the the- 
ories of ingenious and scientific men. Yet, after all, the far- 
mer will find fis fields the most convenient laboratories ; his 
instruments, of husbandry, his satest, most simple and intelli- 
gible apparatus ; his crops his most instructive expositors ; 
and experience his most faithful and unerring guide. 
x 
